EP 0 878 121 A discloses a harvesting machine that can be steered automatically along a crop edge which is scanned with a laser scanning sensor ahead of the harvesting machine. The laser scanning sensor measures, according to the propagation time principle, the distance to the point at which the radiation emitted by the scanning sensor is reflected. On the basis of the position of the crop edge associated with a step-wise change in the distance and its target position, a steering signal is generated that is conducted to a steering controller. In the illustrated embodiments, the laser scanning sensor is attached to the cutter head above the crop edge, but may also be attached to the harvesting machine, on the operator's cab.
EP 0 887 660 A discloses a harvesting machine that is equipped with a laser scanning sensor arranged on the operator's cab. The laser scanning sensor is used for automatically steering the harvesting machine along the crop and/or for determining the amount of crop taken up by the harvesting machine. If the scanning sensor is used during the cereal crop harvest for determining the amount of the crop being taken up by the harvesting machine, the boundaries of the harvesting platform are associated with a pivot angle of the scanning sensor. If a sudden change occurs in this pivot angle region, this leads to the conclusion that a crop edge exists. During plowing the position of the frame of the plow can be determined by a sensor arranged on the plow. On the basis of the output signal of the sensor, the steering arrangement is supplied with a transverse offset distance corresponding to the immediate direction of the operation. In this way the steering arrangement considers the transverse offset of the plow from the tractor. The scanning region of the laser scanning sensor, however, remains independent of the direction of the operation and extends over both possible boundaries of the operation.
Attaching the laser scanning sensor above the edge of the crop being harvested illustrated in EP 0 878 121 A and recognizing the crop edge, the plowed furrow, or the edge of a windrow is particularly simple. However, attaching the scanning sensor to the operating implement (harvesting platform) creates certain disadvantages. The scanning sensor is exposed to strong vibrations that can have a detrimental effect on the accuracy of the measurement. When the operating implement is transferred to a different utility vehicle, the sensor must be transferred from the operating implement to a new operating implement associated with the first utility vehicle. This transfer is time consuming and contains the possibility of damage to the sensor during each installation. By attaching the sensor to the side of the harvesting platform, the sensor can be easily damaged, for example, in headlands or along fence lines. Finally the crop edge or the guide line does not always lie on only one side of the operating implement. Frequently harvesting is performed alternately on the left and the right sides of the harvesting platform. That is not possible with the attachment directly above the crop edge with a single scanning sensor. If a laser scanning sensor used for the automatic steering is attached to the cab in order to avoid these disadvantages, it is problematic to recognize on which side (left or right) the edge of the harvesting crop is located. Furthermore, in the state of the art, the scanning angle region of the laser scanning sensor is fixed, so that it must be selected sufficiently large, so that it detects both the possible boundaries of the operation, but then it will deliver data only at a relatively low scanning rate, but it must be selected smaller in order to produce a higher scanning rate. Then the detection of both possible boundaries of the operation is no longer possible.
DE 197 43 884 A discloses an agricultural machine having an arrangement for recognizing, without contact, the boundaries of operation. The arrangement includes a scanning laser sensor which scans a surface located ahead of the agricultural machine. The boundary of operation is recognized on the basis of the propagation time and the intensity or the phase shift of the reflected radiation. It is proposed that the attachment position and/or the inclination of the sensor be varied manually or automatically, in order to avoid control differences brought about by the relative attachment position.
EP 1 002 455 discloses a scanning sensor whose position can be adjusted manually on a reference line or a reference point. The entire sensor unit is mechanically repositioned. The angular region that was scanned remains constant in each case.